The strong designated verifier ring signature scheme provides signer anonymity to protect actual signer’s identity. However, the message of the strong designated verifier ring signature may disclose some identity information related to the actual signer. To remove this flaw, this study proposes a novel strong designated verifier ring signcryption scheme. Compared with the Han et al. and Huang et al. ring signcryption schemes, the proposed scheme provides strongest signer anonymity to protect the signer identity. This scheme also provides signer admission to show who the actual signer is. Unlike some proposed schemes, which still suffer the message length restriction, this scheme is free from the message length restriction to provide message confidentiality.